Method and apparatus for controlling the temperature of rolls



Oct. 19, 1954 J. P. HOLLOWAY 2,592,113

METHOD AND APPARATUS FOR CONTROLLING THE TEMPERATURE OF ROLLS Filed Feb.25,1949

JA ES'PHILLIP HOLLOWAY 2s 27 4 Patented Oct. 19, 1954 METHOD ANDAPPARATUS FOR CONTROL- LING THE TEMPERATURE OF ROLLS James PhillipHolloway, Manheim Township,

Lancaster County, Pa., assignor to Cork Company, Lancaster, Pa., a

of Pennsylvania Armstrong corporation Application February 25, 1949,Serial No. 78,378

6 Claims.

The present invention is directed to a method and apparatus forcontrolling the temperature of rolls and more particularly to the methodand apparatus for controlling the temperature of a calender roll. Theinvention finds particular usefulness in the asphalt tile field whereproper temperature control at the working surface of the calenderingrolls used in sheet formation is desirable in order to produce a highquality sheet.

In the manufacture of asphalt tile, it is common practice to first millthe composition upon milling rolls and deliver the milled mass in sheetform to a two-roll calender Where the sheet is reduced in thickness anda desired surface finish is effected by the calendering operation.Generally the sheet as delivered to the calender from the milling rollsis at an elevated temperature; and, in order to obtain the desiredsurface finish and prevent excessive adherence of the mass to the rolls,the rolls are internally cooled. Brine is frequently used as the coolantand may be at a temperature of 20 F., for example. The face roll isgenerally maintained at a higher temperature than the back roll (about20 to 30 F. higher) and temperature control on this roll is morenecessary than on the back roll.

It has been found in the manufacture of asphalt -tile that thetemperature at the working surface of the rolls may be controlledeffectively by the circulation of brine within the roll body, except forareas adjacent the roll necks where heat transfer is more rapid than atthe center of the working surface of the roll. The mix which is fed tothe calender in heated condition tends to heat up the working surface toa higher degree throughout the major portion of the area of the workingsurface in contact with the sheet than in the narrow bands beyond theedges of the sheet Where heat is not supplied by the sheet duringformation. As a consequence, such edges of the working surface arerelatively colder than the central portion, and the finished product isdeleteriously affected by such temperature differential because too muchheat is extracted from the sheet adjacent its longitudinal edges.

It "is an object of this invention to provide a method and apparatuswhich will make it possible to extract heat from a roll by internalcooling and apply heat to the edges of the roll adjacent the roll necksto compensate for differences in temperatures existing there, avoidingthe creation of zones at the working surface Where a temperaturedifferential exists and affects proper product formation.

Another object of the invention is to provide a system for controllingthe temperature of an internally cooled roll by the application of heatto the roll in a selected area or areas of the working surface Whereexcessive heat extraction may be encountered.

In order that the invention may be better understood, I shall describethe same in conjunction with the attached drawing in which:

Figure 1 is a diagrammatic view in elevation showing an embodiment ofthe apparatus of the present invention which will be useful in thepractice of the method of the invention;

Figure 2 is a sectional view taken on the line II-II of Figure 1; and

Figure 3 is an enlarged sectional view of one of the heating shoes takenon the line III-III of Figure 1.

In Figure 1 there is shown a two-roll calender which includes aconventional calender framework 2, a top or face roll 3, and a bottom orback roll 3. Both of the rolls may be internally cooled, although onlyone has been shown as provided with a cooling system in the embodimentchosen for illustration. The internal cooling may be effected by meansof a fluid coolant such as brine led into the interior chamber 5 of theroll 3 through an inlet 6 and discharged through an outlet 7. This willbe effective for extracting heat from the working surface 8 of the roll3. In Figure 1 a sheet 9 is shown in section between the rolls 3 and 4.Illustratively this may be a sheet of asphalt tile composition deliveredfrom milling rolls at a temperature in the order of 180 to 250 F., forexample. The sheet may be about /2 inch thick, about 42 inches wide, andof indefinite length. The rolls 3 and t may be set to produce a finishedsheet f inch thick. In operating upon a sheet at such temperature underthese conditions and injecting brine into the cavity 5 at a temperatureof 20 F., the temperature at the working surface 3 of the roll 3 may bein the neighborhood of to F. throughout the major portion of the surface6 which is in contact with the sheet 9. There will be a gradual decreasein the temperature from the roll necks l0 and H to points 12 and E3which are disposed inwardly from the edge of the sheet 9, because heatis conducted rapidly away from the sheet in such zones. Consequently,these areas of the formed sheet are improperly finished and may havecold checks and other defects on the face. In marble type of patterns,the graining will be different in these cold areas than in the remainingportion of the sheet where proper heat extraction has been effected, butnot excessive extraction. The width of the zones where too great anamount of heat is extracted will vary depending upon operatingtemperatures and other conditions.

According to the present invention there is mounted on the machine frame2 for engagement with a portion of the periphery of the roll 3 heatingshoes Ill and i5, one being disposed on each of the edges of the roll 3adjacent the roll necks l and II. One of the shoes, is shown in somedetail in Figures 2 and 3. It includes a bearing bronze shoe l6 whichhas a surface ll of arouate formation adapted to lie in close engagementwith the working surface 8 of the roll 3 as shown in Figures 1 and 2.The shoe [6 is preferably cast and is cored out to provide a chamber 18which preferably receives a heating coil l9 which is positioned closelyadjacent the lower surface of the casting IE and is filled with lead 20to a level about parallel with the upper surface of the coil l9.Insulation material 2| is disposed above the coil and the lead matrixand serves to prevent the loss of heat to the atmosphere, conserving itfor application to the surface portion ll of the shoe. A cover plate 22closes the chamber H3 in the shoe.

A mounting bracket 23 is provided for securing the shoe member to theframe 2 or the machine for free pivotal movement and for a limitedmovement transversely of the pivot so as to permit the shoe to ride infull contact with the working surface 5 of the calender roll. Thebracket 23 is provided with a stud 2A which includes a pivot 25. Theshoe is has a bifurcated extension 28 which is provided with a slottedopening 27 adapted to receive the pivot 25. Jam nuts 28 and 29 areprovided for positioning the shoe i6 on the bracket while permittingfree movement of the shoe about the pivot and also laterally withrespect thereto in the slotted opening 2?. Cap screws Si] and 31 fastenthe bracket 23 to the frame 2.

The width of the shoes will vary depending upon the heatingrequirements, in order to compensate for losses adjacent the roll necks.In the embodiment illustrated, the shoes are about 4 inches wide andextend over about 120 of the circumference of the roll as indicated inFigure 2. Steam at a temperature of about 300 F. has been foundeffective for raising the temperature in the areas in contact with theshoes to a degree where a substantially uniform product is obtained,eliminating the cold cracks and the other defects resulting fromimproper temperature control. The steam temperature or quantity suppliedto the coil 59 through inlets 32 and discharged through exhaust 33 willdepend upon the sheet temperature, coolant temperature, ambientatmospheric temperature, and other variable factors.

While it is preferred to use a steam heating system as shown, the shoesmay be heated with gas flames, for example, and equivalent resultssecured. It will be observed that the shoes are disposed on the upperportion of the rolls where they will not come into contact with materialbeing calendered, and they are effective for heating the outer surfaceof the roll immediately prior to contact of the material to b calenderedwith the roll. The heating is effected continuously as the calenderrotates; and, since the surface of the roll is in contact with thematerial for a relatively short period of time, as the material passesthrough the nip between the rolls, it is not necessary to heat the rollto any substantial depth,

While the invention has been described in connection with the manuactureof asphalt tile, it is not limited thereto, for there are many instancesin other arts where similar problems of temperature control presentthemselves, and the device and method of the present invention willoffer a solution to many of those problems.

While I have illustrated and described a preferred embodiment of theinvention, it will be understood that the same is not limited theretobut may be otherwise embodied and practiced within the scope of thefollowing claims.

I claim:

1. In an apparatus for controlling the temperature at the substantiallycylindrical working surface between the necks of a roll, th combinationof means for injecting coolant into the interior of the roll throughoutsubstantially the entire area of the roll interior which is opposite tothe working surface of the roll to extract heat from the working surfaceand means for supplyin heat directly to the peripheral end portions ofthe outer cylindrical working surface adjacent to the roll necks tocompensate for heat losses from the working surface to the necks.

2. In an apparatus for controlling the temperature at the substantiallycylindrical working surface between the necks of a roll, th combinationof means for injecting coolant into the interior of the roll throughoutsubstantially the entire area of the roll interior which is opposite tothe working surface of the roll to extract heat from the working surfaceand means for supplying heat directly to the peripheral end portions ofthe outer cylindrical working surface adjacent to the roll necks tocompensate for heat losses from the working surface to the neckscomprising metal shoes engageabiewith the outer cylindrical workingsurface adjacent the roll necks, and means for heating the shoes.

3. In a calender including a pair of calender rolls mounted in a framefor rotation, an apparatus for controlling the temperature at the outercylindrical working surface of at least one of the calender rollscomprising means for injecting coolant into the interior of the rollthroughout substantially the entire area of said roll interior which isopposite to the working surface of said roll to extract heat from saidworking surface and means for supplying heat directly to the peripheraiend portions of the outer cylindrical working surface adjacent to theroll necks to compensate for heat losses from said working surface tosaid necks, said last named means comprising a heating shoe having asurface for engagement with a substantial portion of the outercylindrical working surface of the roll at a pcripheral end portionthereof adjacent One neck of the roll, a mounting bracket affixed to thecalender frame, a pivot affixed to th mounting bracket, attaching meanson the shoe having an elongated opening for the reception of said pivot,said shoe being movable with respect to said pivot in a motion ofrotation and in a motion of translation, whereby said shoe is free topivot and move transversely with respect to said pivot to bring saidshoe into engagement with the arcuate surface of the calender roll, andmeans for heating the shoe.

4. In a method of controlling the temperature at the outer cylindricalworking surface of a cooled calender roll against which a heated sheetof plastic material is pressed in calendering, the temperature of thecooled working surface of said roll being substantially lower than thetemperature of said sheet, the steps comprising internally cooling saidroll to extract heat from said working surface of said roll whichengages said sheet, the temperature of which is higher than that of saidworking surface, to thereby obtain a substantially uniform temperaturein the area of the roll which engages said sheet, except adjacent to thelongitudinal edges of said sheet where heat is conducted away from saidsheet at a more rapid rate than at the other portions thereof, andapplying heat to the peripheral end portions of the outer cylindricalworkin surface of said roll in advance of contact of said workingsurface with said heated sheet of plasitc material to increase thetemperature of the cooled Working surface in said peripheral endportions to compensate for such more rapid rate of heat conduction fromsaid sheet adjacent to its longitudinal edges.

5. In a method of controlling the temperature at the outer cylindricalworking surface of a cooled calender roll against which a heated sheetof plastic material is pressed in calendering, the temperature of thecooled working surface of the roll being substantially lower than thetemperature of said sheet, the steps comprising circulating a coolantinteriorly of said roll to reduce the temperature at said workingsurface of said roll to a degree substantially below the temperature ofsaid heated sheet of plastic material to be calendered and applying heatto the peripheral end portions of the outer cylindrical working surfaceof said roll to compensate for a more rapid rate of heat conduction fromsaid sheet to said r011 adjacent to the longitudinal edges of saidsheet.

6. In a method of controlling the temperature at the outer cylindricalworking surface of a cooled calender roll against Which a heated sheetof plastic material is pressed in calendering, the temperature of thecooled working surface of the roll being substantially lower than thetemperature of said sheet, the steps comprising interiorly cooling saidroll to extract heat from said working surface of said roll which is toengage said sheet, bringing said heated sheet of plastic material intoengagement with said working surface with said sheet at a temperaturesubstantially above the temperature of said working surface, anddirectly applying heat to the peripheral end portions of said outercylindrical working surface of said roll in an amount sufficient tobring said working surface in such areas to a degree substantiallyequivalent to the temperature of other portions of said working surfacein direct contact with said sheet being operated upon.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,519,314 Koupal Dec. 16, 1924 1,638,626 Fox Aug. 9, 19271,699,902 McCrery Jan. 22, 1929 1,978,894 Clark Oct, 30, 1934 2,184,908Chan Dec. 26, 1939 FOREIGN PATENTS Niunber Country Date 512,636 GermanyNov. 15, 1930

